mercredi 10 septembre 2008

There's always great news and tips in the PowerScripting Podcast, this time there's a great deal : if you follow the link provided in the 40th edition, you'll be able to get a FREE licence of PowerShellPlus !

Just on thing to do : go to PowerScripting Podcast site, listen to this great talk-show on PowerShell, and follow the link to PowerShellPlus Beta : once it's available, you'll get your free licence !

Well, a lot of things are coming ! first the source code.. but others widgets are ready to strike. I'm now working on cleaning up the code, making more error handling in PowerShell, Transform the Visifire PowerShell code...

I came across a little problem, and we got the same with standard silverlight Datagrid :

How to dynamically build the datagrid ?

AgDatagrid and Silverlight Datagrid use IList type to build the control Datasource. When using managed code (C# or VB.NET in silverlight development), you need to build a Class representing your data to build the IList :

1:publicclass Person {

2:publicstring Name {

3: get;

4: set;

5: }

6:

7:publicstring City {

8: get;

9: set;

10: }

11:

12:publicstring State {

13: get;

14: set;

15: }

16: }

17:

18:new Person() {

19: me = "Michael Jordan", City="Chicago", State="IL" },

20:new Person() {

21: me = "Kobe Bryant", City="Los Angeles", State="CA" },

22:new Person() {

23: me = "Shaquille O'Neil", City="Miami", State="FL" },

24:new Person() {

25: me = "Patrick Ewing", City="New York", State="NY" }

26:

That's ok when you know what kind of data will be bound to the grid, but how to do this when you have dynamic content ?

I plan to use this grid to represent data coming from PowerShell... So I don't know how many column and type of Data I'll have to implement.

here is the point :I can't use a static class to define my Data in the Silverlight Control.

Game Over ?

Not Yet!

We could follow two path to achieve this :

Use Dynamic Language programming with Silverlight (ironPython,ironRuby, Managed JScript...) that let us build dynamically the control ?

Dynamically build the class in managed code ?

Using Dynamic language will be an elegant (and for me the best) way to do it. However, we're dealing with Beta version here, and it's not so easy to use external control and SL2B2 controls in this context (yet), so I won't explain it for now (waiting for the MS Silverlight Team to publish some samples on it ;) )

So, could we dynamically build the Class in our managed code ?

my answer is : YES !

How to generate typed objects dynamically

After some search (HEAVY search should I say), I just found this marvelous thread from Vladimir Bodurov on "how to generated dynamically typed objects in .NET :

lundi 7 juillet 2008

Update : People asked me a preview of Poshboard to play with it : so be it ! A preview is now available on codeplex here, or follow this link : http://www.codeplex.com/poshboard

Here's a little video of my "coming soon" open source project called "PowerShell Dashboard" (PoshBoard for friends). This project will be available soon on the open source forge of my company Octo Technology.

The goal of this project is to deliver modular web portal based on PowerShell. The idea is to use Web GUI like igoogle, PageFlakes or Netvibes, for IT Admin and infrastructure management.

This will let you easely build infrastructure dashboards without the need to code in ASP.NET / AJAX / C# or other compiled language :

All you need to know is scriptingAll you need to have is imagination.;)

This project is based on Dropthings, a great ASP.NET/AJAX open source project by Omar Al Zabir, turned to an intranet project.

For this first teaser, I show you a first widget to generate Silverlight charts directly fom PowerShell scripts. I've used Chart generation (Column, pie...) with the great Silverlight charting library VISIFIRE (free and open source too)

This first demonstation presents the general concept of the web portal. It'll be freely available in the coming weeks. Then I'll propose several componants and innovations that will let you have much fun with PowerShell development ! :)

lundi 26 mai 2008

This is the third and last part of this little Tutorial on PowerShell and ASP.NET.

We will discuss about managing script from a webform and how to deploy this website on a IIS server.

Manage script

We saw previously how to execute PowerShell code from a Textbox. We will now learn how to manage on-the-fly changes on a prebuild PowerShell script.

This is a good method when you want, for example, create à provisioning or audit web portal. User won't write directly PowerShell code, but will fill a form that will then call a script with arguments.

To illustrate this, here is another example with a WMI request engine that takes a machine name as parameter. I slightly modified our former example : I added a Textbox to put a machine Name :

Let's see what changed in our code. Ny the way, not much things : We will now read a embbeded Script and modify is content before execution.

A classic PowerShell WMI request. As you can see, I put the Machine name as an argument on the first line. I gives an arbitrary name "*ComputerName*" that will let us replace it with the content of the Textbox.

The important thing here is to have unique name in the script when you want to do this change (here *computername* is used only once). This is easy to achieve, because you're the Writer of the POwerShell Code ;)

That's the deal, now we execute the PowerShell code as before :

this.executePowerShellCode(strContent);

Nothing really tricky here. If you need to modifiy your request engine, you only need to edit the .PS1 file, no C#/ASP.NET is required (this can be delegate to every administrator that got skills on PowerShell)

You can of course put several parameters in your web form. The limit is your imagination (and business needs, by the way). There's many little things to implement in order to have a "Profesionnal" powershell website (Error handler, better output support...), but you now have the bases to achieve this. Hope you got a better view of PowerShell/ASP.NET interaction.

To finish this tutorial, let's see how to publish the website on IIS.

WebSite deployment

Our main goal is to use a Service Account to execute tasks (here, our scripts). This simplify the rights management process and delegation, cause it's not necessary to gives administrator rights to every user of the website.

We only need to know the identity of the end user and filter website access.

The deployment strategy on IIS is :

First, Filter the website access. Just put appropriate rights on the website folder (put a user group on the folder with read access only).

Nothing special here, I just put some parameters like multiline suspport and colors to match PowerShell console.

Then there is the Execute button and the output Textbox. They are embbeded in a UpdatePanel Control. This control let us refresh only this elements without refreshing the whole page when we'll update content. You can see our Timer too :

The Interval parameter (Interval="100") define the refresh rate (milliseconds), the OnTick (OnTick="Timer1_Tick") specify the function called in the code-behind when the Timer refresh. The Timer is desactivated by default (Enabled="False") in order to avoid useless charge on the serve. It's activated only when the Button is clicked.

That's all for the user interface. Except the UpdatePanel (which is only another control from the designer point of view), we are really on a classic webForm design. We will no study the Code-Behind part of the website.

DEFAULT.ASPX.CS

This is the C# Code that will manage our PowerShell execution and the update of the output Textbox.

Let's go from the beginning : At the very top of the code, I just add 3 more instances (all the others are generated by default when you create an asp.NET project website) :

using System.Management.Automation;

using System.Management.Automation.Runspaces;

using System.IO;

System.Management.Automation and .Runspaces are required to create the PowerShell runspace and the Pipeline. System.IO will be use to convert the Input Textbox content as you'll see later.

We'll then first create Runspace and Pipeline object at the beginning of the main class to expose them in all functions.

Runspace runspace = RunspaceFactory.CreateRunspace();

Pipeline pipe;

We will now study the code, beginning from the user interaction : the Click on the Button. The function (line 85) is :

// Gather script from the TxtPowerShellScript and convert it from html to clean text

// then call executePowerShellCode function with the result

string strContent = TxtPowerShellScript.Text;

StringWriter writer = new StringWriter();

Server.HtmlDecode(strContent, writer);

this.executePowerShellCode(writer.ToString());

}

Let's see what happen. First, I create the strCurrentID string that will hold the current user name. This is not mandatory for our example, but this information is interesting to monitor our website activities.

When we'll deploy our site, it's a Service Account that will handle all the code execution. as we want (if it's not the case, you should!) monitor the Site Activities, it's important to know the name of the user who fired an action, in order to know who to blame if something goes wrong :)

System.Security.Principal.WindowsIdentity.GetCurrent().Name gives us this info.

Then we activate the Timer:

this.Timer1.Enabled = true;

We desactivate the button (to avoid unwanted launch of script while another is running):

this.BtnExecuteScript.Enabled = false;

And we reset the Output Textbox :

this.TxtResult.Text = "";

Then we will create our Session Variable that I called "PowerTrace". We feed it first with the name of the user :

Let's go deeper on this point. All our problem here is to pass data from our code behind to the aspx controls (output textbox) when we refresh the page. As these 2 elements are isolated (each has its context : WebForm on the client side, codebehind on the server side), we need a way to put the output of our script in the Output Textbox.

There is several solutions, more or less smart (Create temporary textfile, add output as an URL element...). The Session VAriable is in our context the best and simple way to do this. This let you present datas to the user-side of the website that lives until the user session ends. Without this, when we refresh the page, every informations that are on the server side (variables from the codebehind) will be reset.

As the script output won't takes a lot of Memory and our website is targeted to be an intranet solution for administrators, this is a good choice, easy to setup.

The content of this variable will be exposed until the end of the user session. Now we'll gather the content of the Input Textbox :

string strContent = TxtPowerShellScript.Text;

Problem here : We are in an HTML Context, the content of the Textbox is in HTML format. This won't let us execute the code as is, cause unwanted informations are added ("\r\n" for carraige return...). We can't use this code with PowerShell like this.

We are lucky : there is a method that let us do just that : convert HTML string to standard text string. It's name is HTMLDECODE

This is this method that I use here : I create a StringWriter object (to build string), and use the HTMLDECODE method :

Nothing special, I use a really classic way to execute Powershell code async. You'll find many sample on internet that do just that.

We open a new runspace

runspace.Open();

Then we create a piepline in this runspace, with the code from the Input Textbox

pipe = runspace.CreatePipeline(code);

We close the Pipeline Input

pipe.Input.Close();

We then create a Event manager. It calls the "Output_Dataready" function when something appears in the pipeline output.

pipe.Output.DataReady += new EventHandler(Output_DataReady);

We create another Event manager. It calls the "pipe_StateChanged" function when the state of the pipeline Changed. Here, we test if the pipeline state is "Terminated", wich told us that the script ends. Then we will do some things, like activate the button again (we'll speak of that later)

Finally, we call the "InvokeAsync" method that will execute the pipeline asynchronously.

pipe.InvokeAsync();

Ok, now our code is waiting for activities from the pipeline. We'll now look at the functions "Output_Dataready" when data arrived at the pipeline output .

void Output_DataReady(object sender, EventArgs e)

{

PipelineReader<PSObject> reader = (PipelineReader<PSObject>)sender;

String strPowershellTrace = reader.Read().ToString();

Session["PowerTrace"] += strPowershellTrace + "\r\n";

}

We first read the objects in the pipeline output and put it in a reader object :

PipelineReader<PSObject> reader = (PipelineReader<PSObject>)sender;

Then, we create a string variable wich get the output from the pipeline (script output)

String strPowershellTrace = reader.Read().ToString();

Finally, we add this variable in our Session Variable

Session["PowerTrace"] += strPowershellTrace + "\r\n";

As you can see, I add "\r\n" at the end to handle carriage return in HTML (this output will be in a HTML Textbox). To conclude this part on PowerShell code exectution, let's have a look on the last function when the pipeline state changes.

Here, we put a condition on the pipeline state : if the status is completed, we do some actions, else we do nothing (we only need for the example to test if our script execution is completed)

if (pipe.PipelineStateInfo.State == PipelineState.Completed)

…

So, what we do here ? First we close the runspace

Runspace.close();

Thens, while our Session Variable isn't null AND there's something in it (Number of caracters greater than zero), we don't do anything. We do this to let time for our Timer to write the Session Variable data in the Output Textbox. We'll see after how and why